code: def is_subiteration(a, b):
      """
      returns True if that each hash sequence in 'a' is a prefix for
      the corresponding sequence indexed by the same node in 'b'.
      """
      return all(
          b[node][: len(hashes)] == hashes for node, hashes in a.items()
      )
  
imports: import pytest
  import networkx
  from networkx.generators import directed
label_desc: Use image node_id 11 for calling a global function with example usage: is_subiteration(a, b) and returns: all